Printing telegraph system



Fe. 25, 1936. T, 1N 2,031,934

PRINTING TELEGRAPH SYSTEM Filed July 12, 1934 2 Sheets-Sheet l INVENTOR 7'. L. C ORW/N yww ATTORNEY Feb. 25, 1936.

T. L. CORWIN PRINTING TELEGRAPH SYSTEM Filed July 12, I934 2 Sheets-Sheet 2 ATTORNEY Patented Feb. 25, 1936 STATES PATENT OFFICE PRINTING TELEGRAPH SYSTEM Thomas L. Corwin, Newark, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 12, 1934, Serial No. 734,709

'12 Claims.

the motors at subscribers printing telegraph stahome are arranged to be remotely controlled over either normally closed or normally open loops.

In a communication system where the demands on distant teletypewriter motors are not continuous, such as in a light traflic printing telegraph system, it is desirable to operate the motors only when the Working of the system requires such operation. This will reduce current consumption and maintenance expense. Several types of arrangements have been developed for performing this function.

For systems in which the transmission lines are normally closed, it has been found that in the case of those arrangements which are designed ':to start motors in response to the closure of the transmission lines following a short open period, false operation may occur. For example, if a switchboard operator should stop the motor at a subscribers station and in withdrawing the :plug from the line jack cause a momentary interruption of line current, the motor at the subscribers station would start and continue to run without the knowledge of the switchboard operator. A subscribers motor might also be unintentionally started by the swinging together of open wire lines, by an induced surge of current due to lightning, or by any other cause which would result in a momentary cessation of line current.

The false operation of remotely controlled teletypewriter motors is objectionable in that a motor at a subscribers station may be caused to start and continue to run without the knowledge of the switchboard operator. This wastes current from the power supply at that particular station and causes needless wear of the teletypewriter apparatus at that station.

t is an object of the present invention to provide improved unattended teletypewriter exchange service over both normally closed and normally open loops. I

Another object of this invention is to enable an operator at a sending printing telegraph station to start and stop the motor of a receiving teletypewriter, located at an unattended printing telegraph station, in an improved manner.

Still another object of this invention is to provide an improved arrangement at a subscribers station for giving a signal to an operator at a central oflice to indicate that the subscribers 10- cal source of power supply has been connected to his motor.

A further object of the invention is to provide an improved arrangement at a subscribers station for giving a signal to an operator at a cen- 5 i 4 tral ofiice to indicate that the subscribers motor has attained its full operating speed.

In accordance with this invention, when an operator at a sending printing telegraph station wishes to start the motor of a receiving teletypewriter located at an unattended printing telegraph station, the operator causes her sending teletypewriter to transmit significant current variations over a normally closed telegraph line to the receiving teletypewriter apparatus. significant current variations should consist of a series of alternate openings and closures of the telegraph line connecting the two stations and should be so rapid that they, in effect, comprise pulsating direct current. known permutation code of signals is used, these significant current variations could comprise a series of S signals.

When these significant current variations arrive at the unattended station, they actuate an 25.

alternating current relay located at the unattended station and connected into the telegraph line. The actuation of this alternating current relay causes it to operate its armature and to thereby close a path for current, from a source of power supply also located at the unattended station, to actuate another relay. The actuation of this second relay causes it to operate its armature and to thereby close a path for current from the power supply source to start the motor of the receiving teletypewriter located at the unattended station and to also look up this second relay. At the same time, a resistance which is normally connected in the line is short-circuited. This causes an increase in the line current which, in 40 effect, gives a signal to an operator at the central ofiice to indicate that the subscribers apparatus is in condition for communication.

After communication between the two stations has ceased, the operator at the sending station transmits a preassigned signal, such as upper case H. When this preassigned signal is received at the unattended station, it operates a contact which opens the locking-up circuit of the second relay at the unattended station. This causes the second relay to release its armature and thereby open the path leading from the power supply source to the motor of the receiving teletypewriter. As a result, the motor stops.

In order to prevent false operation due to un- These 15'- When a certain well 20.

lay 6.

- controlarrangement.

as those caused by line hits, a modification of this invention employs a delay arrangement located at the unattained station. This delay arrangement includes a direct current relay of the slow-to-operate type and a rectifying device, such as a Rectox unit, connected in parallel with the direct current relay. When the alternating current relay is now operated, it closes a path for current from a source of alternating current to pass to the direct current relay and the rectifying device. The rectifying device requires a certain amount of time in which to operate after which the direct current relay connected in parallel with it will also operate. In operating, the direct cur-- rent relay closes a path for current from a source of power supply to operate a third relay corresponding to the second relay in the case mentioned above. This third relay locks up and connects the power supply to the motor thereby starting the motor. The motor is stopped in the same manner as that described above.

,The invention will now be described in detail with reference to the drawing in which:

Fig. 1 shows a preferred embodiment for closed loop operation;

Fig. 2 shows an alternative arrangement for closed operation;

Fig. 3 shows a preferred embodiment for open loop operation;

Fig. 4 shows an alternative arrangement for open loop operation;

Fig. 5 shows the details of a centrifugal contact device used in the arrangements shown in Figs. 2 and 4; and Fig. 6 shows the form of an S signal used for starting the motor of an unattended teletypewriter.v

'As previously explained, the subscribers station is arranged so that the motor is started and the apparatus made ready to receive printer pulses by the sending from the central ofiice of rapidly alternating marking and spacing signals, such as a series of S signals. As is shown in Fig. 6, each signal comprises practically alternate spacing and marking impulses.

Referring now particularly to Fig. 1, which shows a preferred embodiment of the invention for closed loop operation, the effect of sending ;S signals is to open and close the line momentarily a number of times thereby causing the operation of alternating current relay 8. The circuit of the operation of this relay 8 is traced from positive battery (not shown) at a printing telegraph station, such as central office I, over line conductor 2, through sending contacts 4, selector magnet 5, relay 6, resistance I, and then to negative battery in the central ofiice I over line conductor 3. In parallel with relay 6 and ,resistance 7 are alternating current relay 8 and ceived by the subscribers station, relay 8 operates, but relay 6, which is of the slow releasing type, does not release. The operation of relay 8, however, through its upper make contacts, shortcircuits relay 6, thereby causing the release of re- Relay 6 is of the sloW-to-release type, so that momentarily open circuits on the line will not cause the apparatus to lock-in. Thus, relay 6 acts as a control means for insuring against false or unintentional operation of the motor intentional openings of the telegraph line, such With relay 6 deenergized, a circuit is closed to operate power relay It). This circuit is traced from the grounded power supply conductor I? from a source of alternating current power through the inner front contacts of alternating current relay 8, the back contacts of relay 6, and then through the winding of relay II! to power supply conductor I6. This operates relay I and locks-in a path traced from power supply conductor I6, winding and upper front contacts of relay II), emergency stop key I 2, stop bar contacts I3, to grounded power supply conductor IT. The operation of relay II] also closes a circuit from the power supply to motor I5, causing motor I to rotate. This also closes a circuit to rectifier I4, which may be any well known rectifying apparatus, such as a fullwave copper oxide rectifier.

After an interval, during which motor I5 is allowed to come up to full speed, rectified current from rectifier I 4 operates relay II. The operation of relay II short-circuits the network consisting of relay 6 and resistance I in parallel with relay 8 and condenser 9, thereby placing selector I magnet 5 in condition for receiving printer pulses. The short-circuiting of resistance I reduces the resistance at the subscribers station. This increases the current fiowing in the line (conductors 2 and 3). This increase in line current, in

eifect, gives a signal to an operator at the central oflice I to indicate that the local source of power supply has been connected tothe subscribers motor.

The subscribers substation apparatus remains in a position to receive printer pulses with the motor I5 running until a prearranged character, such as upper case H, is sent as a stopsignal. When this character is received, the locking circuit to relay II] is broken at stop bar contacts I3 (by selecting mechanism and junction bars of the sub- I comprising relay 6 and resistance 1 in parallel with relay 8 and condenser 9, and restores the line to its v normal non-operated condition.

An alternate method of procuring the same result for closed loop operation is shown in Fig. 2. In this case, when the line is opened and closed repeatedly due to the sending of S signals, relay 24 operates in a circuit traced from positive battery (not shown) from central office I8 over line conductor I9, through sending contacts 2!, selector magnet 22, alternating current relay 24 and condenser 25 in parallel with resistance 23 and then over line conductor 2|] to negative battery at central office I8.

If alternating current relay 24 remains operated long enough it will cause the operation of slow-tooperate relay 2?. The circuit for the operation of relay 2'! is traced from grounded alternating current power supply conductor 34, through the contacts of relay 24, winding of relay 2'! in parallel with rectifier 26, to power supply conductor 33. Rectifier 26 may be any well known rectifying device, such as a copper oxide rectifier. During the negative half cycle the resistance of rectifier 26 is in the'high direction and the current is forced through relay 27, but during the positive half cycle it is in the conducting direction and the current goes through rectifier 26 rather than through relay 21. Relay 2! therefore receiveshalf-waverectified pulses and due to this fact and to the fact that it is of slow-operating construotion,:it is slow to close its contacts, so that momentary open cir- :cuits on the line which might cause the momentary operation of relay 24, do not cause relay 21 to operate and lock-in the subscribers station apparatus. This insures against faulty or unintentional operation of the motor control arrangew: :ment.

With repeated opens and closures of the circuit due to the sending of S signals, relay 24 is held operated long enough to cause the operation of relay 21. Relay 2'! when operated, causes relay 28 to 151 operate in a circuit traced from grounded power ,.to that described for Fig. 1.

full operating speed, centrifugal device 3| (shown in detail in Fig. 5) closes its contacts and shortcircuits the network comprising relay 24 and condenser in parallel with resistance 23 The short-circuiting of resistance 23 reduces the resistance of the subscribers set and increases the line current as a signal to the operator at central ofiice I8 that the subscribers motor has attained its full operating speed.

Asin the case of Fig. 1, the subscribers station .apparatus remains in condition for receiving printer pulses with the motor 32 running until a prearranged character, such as upper case H, is sent as a stop signal. When this character is received, selecting mechanism of the subscriber's teletypewriter operates a function bail which opens the stop bar contacts thereby breaking the locking circuit for relay 28 and thus causing relay 28 to release. The release of relay 28 opens the circuit to motor 32, allowing the motor to come to rest and the contacts of centrifugal device 3| to open. The opening of the contacts on centrifugal device 3| removes the short circuit from the network comprising relay '24 and condenser 25 in parallel with resistance 23 and restores the line to its normal non-operated condition.

Fig. 3 which is a preferred embodiment of the invention for open loop operation is arranged to lock-in and start the motor in a manner similar In this case, the

'S signals from central office ID'I operate alternating current relay I08 in a circuit traced from battery at central ofiice IOI over tip line wire I02 through sending contacts I04, selector magnet I85, back contact of relay III, through alternat- 'ing current relay I08 and condenser H19 in parallel with relay I06 and resistance I01, and then to ground. Relay IE6 is of the slow-releasing type and does not release on the S signals. The

operation of relay I98 short-circuits relay I06 through the upper front contacts of relay I08 and relay I06 releases after a time interval. Relay I is made slow in releasing so that momentary open circuits on the line will not cause the apparatus to lock-in and start the motor.

With relay I08 in an operated position and relay IIJB in a released condition, a circuit is closed to operate power relay I II). This circuit is traced from grounded power supply conductor II 'Linner front contact of relay I08, contacts of relay IIIB,

through the winding of relay III), and then to power supply conductor H6. When relay II'II operates, it locks-in by a path traced from power supply conductor IIB, winding and upper front contacts of relay IIII, emergency stop key I I2, stop bar contacts I I3, and then to grounded power supply conductor III. The operation of relay III) closes a circuit from the power supply to motor 5 thereby causing motor II5 to rotate. Relay III) also closes a path to rectifier 4 which may be any well known rectifying apparatus, such as a full-wave copper oxide rectifier. After a time interval during which motor II5 is allowed to come up to full speed, rectified current from rectifier II 4 operates relay III.

The operation of relay III removes the net work comprising relay I06 and resistance III! in parallel with relay I08 and condenser I39 from the tip conductor I02 and closes the circuit between the tip conductor I02 and the ring conductor I03 thereby placing selector magnet I05 in condition for receiving printer pulses. When resistance IN is cut out of the circuit, this increases the line current thereby giving a signal to the central office IOI that the subscribers local source of power supply has been connected to his motor.

The subscribers apparatus remains in condition for receiving printer pulses with the motor I I5 running until a preassigned combination of significant current variations, such as those assigned to upper case H, is sent as a stop signal. When these current variations are received they operate selecting mechanism which causes the operation of the stop bar contacts II3. When contacts II3 open they open the locking-up circuit for relay III] and cause it to release. The release of relay II-I! opens the circuit to motor I I5 thereby causing the motor I I5 to come to rest. It also causes the removal of the power line voltage from rectifier II4. This causes the direct current to disappear from the output terminals of rectifier H4 and permits the release of relay III. When relay II I releases, it restores the line to its normal non-operated condition with the network composed of relay I06 and resistance III! in parallel with relay I08 and condenser I09 connected from the tip conductor I02 to ground.

Fig. 4 shows an alternate arrangement for obtaining the same result for open loop operation. In this case, when the line is opened and closed repeatedly due to the sending of S signals, alternating current relay I24 operates. The circuit for the operation of relay I24 is traced from battery from central office I I8 over tip conductor I|9 through sending contacts I2I, selector magnet |22, back contacts of centrifugal device I3I, through relay I24 and condenser I25 in parallel with resistance I23, and then to ground. If relay I24 remains operated on these S pulses for a sufiiciently long interval, it will cause the operation of slow-to-operate relay I21: The circuit for the operation of relay I 21 is traced from grounded alternating current power supply conductor I34 through the contacts of relay I24, winding of relay I2'I in parallel with rectifier I26 to power supply conductor I33. Rectifier I26 may be any well known rectifying device, such as a copper oxide rectifier. The action of this combination of relay I21 and rectifier I26 is the same as that described above for relay 21 and rectifier 26 shown in Fig. 2.

When relay I2'I operates, it closes a path from grounded power supply conductor I34, contacts of relay I2I, through the winding of relay I28,

Ii I) and then to power supply conductor I33. Relay I 28 operates on this current and looks through a path from conductor I33, upper contacts of relay I28, emergency stop key I29, stop bar contacts I30, and then to conductor I34. The operation of relay I28 also closes a circuit from the power supply to motor I 32 causing the motor I32 to rotate. When motor I32 has reached its full speed, centrifugal device I3I (shown in detail in Fig. 5) breaks its back contacts and closes-its front contacts, thereby removing the network comprising relay I24, condenser I25 and resistance I23 from the tip side of the line and connecting the tip line wire H9 through selector magnet I22 to ring conductor I20, thus placing the subscribers apparatus in condition for receiving printer pulses. The removal of resistance I23 from the circuit increases the line current which, in effect, gives a signal to the central ofiice operator at central ofiice M8 to indicate that the subscribers motor has attained its full operating speed.

As in the other cases, the motor I32 is left running until a prearranged character, such as upper case H, is sent as a stop signal. When this character is received, the locking circuit for relay I28 is broken at stop bar contacts I30 and relay I28 is allowed to release. The release of relay I28 opens the circuit through motor I32 thereby causing the motor I 32 to come to rest and the centrifugal contact device I 3! to open the circuit between the two line conductors I I9 and I20 and reconnect the network comprising relay I 24, condenser I25, and resistance I23 to the tip conductor H9. This restores the line to its normal non-operated condition.

Fig. 5 shows the details of the centrifugal con tact device used in Figs. 2 and 4. It is of the well known fiyball governor type in which, upon the rotation of shaft I50 which is connected to themotor,' the bracket I5I and arms I52 with fly-'- balls I53 rotate with it. When the motor has reached its full operating speed, the centrifugal force (due to the rotation) forces the flyballs I53 outward and causes arms I52 to rotate on their pivots thereby pushing the operating shaft I54 in a longitudinal direction to the left against the pressure of retractile spring I55. The motion of shaft I54 in a longitudinal direction to the left causes armature I55 to break the circuit with its back contact I51 and make the circuit with its front contact I58. Conversely when the motor slows down, flyballs I53 will drop inwardly and cause arms I52 to resume the position shown in Fig. 5. This will pull the operating shaft I55 back to the right which, in turn, causes armature I56 to break its front contact I58 and make its back contact I51.

The above arrangements have been shown in order to'illustrate the principles of this invention. a It is to be understood that different arrangements employing the principles of this in-- vention may be designed. Accordingly, the invention is not to be limited to the arrangements shown in the drawing but is to be restricted only by the claims appended hereto.

What is claimed is:

11. A communication system including a first communication station connected by a transmission line to a second communication station; said second communication station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and in-' strumentalities for connecting the source of power telegraph line which normally has direct current flowing over it, said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities including an alternating current relay located at the second station and adapted to be operated by the reception at the second station of a series of rapidly alternating marking and spacing impulses transmitted over the telegraph line by the first station. I

3. A printing telegraph system including a first printing telegraph station connectible by a nor mally open loop to a second printing telegraph station; said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, control means for closing said normally open loop, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities including an alternating current relay located at the second station and adapted to be operated by the reception at the second station of a series of rapidly alternating marking and spacing impulses transmitted over the telegraph line by the first station.

4. A printing telegraph system including a first printing telegraph station connected by a telegraph line to a second printing telegraph station; said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and instrumentalities for, connecting the source of power supply to the motor, said instrumentalities being operated bythe reception at the second printing telegraph station of pulsating direct current transmitted over the telegraph line by the first printing telegraph station; and controlmeans for insuring against false or unintentional operation of said instrumentalities.

5. A printing telegraph system including a'first printing telegraph station connected by a telegraph line to a secondprinting telegraph station; said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities being operated by the reception at the second printing telegraph station of a series of rapidly alternating marking and spacing impulses transmitted over the telegraph line by the first printing telegraph station; means for insuring against false and unintentional operation of said instrumentalities, and said control means including an electro-responsive device having a time delay.

6. A printing telegraph system including a first printing telegraph station connected by a telegraph line to a second printing telegraph station;

and control said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor, but normally disconnected therefrom, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities being operated by the reception at the second printing telegraph station of pulsating direct current transmitted over the telegraph line by the first printing telegraph station; and control means for insuring against false and unintentional operation of said instrumentalities, said control means including a relay of the slow-to release type.

7. A printing telegraph system including a first printing telegraph station connected by a telegraph line to a second printing telegraph station; said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities being operated by the reception at the second printing telegraph station of a series of rapidly alternating marking and spacing impulses transmitted over the telegraph line by the first printing telegraph station; and control means for insuring against false or unintentional operation of said instrumentalities, said control means including a rectifying device.

8. A printing telegraph system including a first printing telegraph station connected by a telegraph line to a second printing telegraph station; said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities being operated by the reception at the second printing telegraph station of pulsating direct current transmitted over the telegraph line by the first printing telegraph station; and control means for insuring against false or unintentional operation of said instrLunenta-lities, said control means including a copper oxide rectifier.

9. A printing telegraph system including a first printing telegraph station connected by a telegraph line to a second printing telegraph station; said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities being operated by the reception at the second printing telegraph station of a series of rapidly alternating marking and spacing impulses transmitted over the telegraph line by the first printing telegraph station; and signaling means for accurately informing an operator at the first printing telegraph station whether the instrumentalities have operated to connect the source of power supply to the motor and whether the motor has come up to its full operating speed.

10. A printing telegraph system including a first printing telegraph station connected by a telegraph line to a second printing telegraph station; said second printing telegraph station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities being operated by the reception at the second printing telegraph station of a series of rapidly alternating marking and spacing impulses transmitted over the telegraph line by the first printing telegraph station; and signaling means for giving an indication to the operator at the first printing telegraph station that the instrumentalities have operated to connect the source of power supply to the motor and that the motor has come up to its full operating speed, said signaling means including a resistance located at the second printing telegraph station and normally connected to the telegraph line, and a centrifugal contact device connected to the shaft of the motor for increasing the line current by short-circuiting the resistance when the motor has attained its full operating speed.

11. A printing telegraph system including a first printing telegraph station connected by a telegraph line to a second printing telegraph station, said second station having a teletypewriter, a motor for operating the teletypewriter, a source of power supply for operating the motor but normally disconnected therefrom, and instrumentalities for connecting the source of power supply to the motor, said instrumentalities including a relay which requires that a plurality of successive code impulse combinations pass through its winding before it will operate, and control means at the first station for transmitting a plurality of successive code impulse combinations over the telegraph line to the second station for operating the relay.

12. In a teletypewriter system having a first teletypewriter station and a second teletypewriter station with a telegraph line extending from the first station to the second station, said second station having a teletypewriter with an energizing circuit which is normally open and adapted to be closed in response to the operation of an alternating current relay also located at the second station, the method of starting the teletypewriter motor at the second station from the first station which comprises transmitting pulsating direct current from the first station over the telegraph line to the second station, operating the alternating current relay, and closing the energizing circuit of the motor.

THOMAS L. CORWIN. 

